Pre- and post-process bore gaging using a honing feed system equipped with feed force sensing

Abstract

The method of the invention provides a capability for accurately and uniformly determining the sizes of bores of workpieces, both pre- and post-process, to improve process control, particularly compensation for tool or stone wear and other factors, and process data collection. The present method makes all required bore measurements, including those in both the workpiece bore and the calibration ring or sample workpiece bore, with the honing tool, under controlled static, non-honing conditions, including expanding the tool in the bores in a predetermined manner, such as at a predetermined rate. The method of the invention has utility for honing multiple workpieces to a finished size with a single tool, and also for multiple spindle applications.

1. A method of determining a size of a bore of a workpiece honed using a honing tool assembled to a honing machine feed system capable of measuring feed forces exerted against the tool and feed system positions representative of feed positions of the tool, comprising steps of:
 expanding the tool within the bore of the workpiece, under static conditions, until a predetermined feed force is reached, and measuring the feed system position; 
 positioning the tool in a bore of known size and expanding the tool, under the static conditions, until the predetermined feed force is reached, and measuring the feed system position; 
 determining a value representative of the size of the bore of the workpiece, as a function of the measured feed system position for the tool in the bore of known size, and the measured feed system position for the tool in the bore of the workpiece. 
 
     
     
       2. A method as claimed in  claim 1 , comprising a further step of utilizing the value representative of the size of the bore of the workpiece for statistical process control. 
     
     
       3. A method as claimed in  claim 1 , comprising steps prior to the honing of the bore of the workpiece, of:
 determining a value representative of predicted stone wear for honing the bore of the workpiece; 
 determining a target feed system position for honing the bore of the workpiece to a target size, as a function of the target size and the value representative of predicted stone wear; and 
 honing the bore of the workpiece until the target feed system position is reached. 
 
     
     
       4. A method as claimed in  claim 3 , wherein the value representative of predicted stone wear is determined as a function of an amount of stock to be removed by the honing of the bore to the target feed system position. 
     
     
       5. A method as claimed in  claim 4 , wherein the value representative of predicted stone wear is determined at least in part, from measurements of stone wear for at least one previously honed workpiece. 
     
     
       6. A method as claimed in  claim 1 , wherein the steps of expanding the tool comprise expanding the tool at a predetermined rate. 
     
     
       7. A method as claimed in  claim 1 , comprising an additional step of determining a feed system compensation value as a function of the measured feed system position for the tool in the bore of known size, and the measured feed system position for the tool in the bore of the workpiece. 
     
     
       8. A method as claimed in  claim 7 , comprising a further step of determining a target feed system position as a function of the feed system compensation value and a value representative of predicted stone wear for a subsequent honing step. 
     
     
       9. A method as claimed in  claim 7 , comprising an additional step of using the feed system compensation value for determining a target feed system position for honing the bore using another honing tool. 
     
     
       10. A method as claimed in  claim 1 , wherein the bore of known size comprises a bore of a calibration ring or a sample workpiece. 
     
     
       11. A method of honing a bore of a workpiece using a honing tool assembled to a honing machine feed system capable of measuring feed forces exerted against the tool and feed system positions representative of feed positions of the tool, comprising steps of:
 expanding the tool within the bore of the workpiece, under static conditions, until a predetermined feed force is reached, and measuring the feed system position; 
 determining a predicted feed system compensation value for tool wear for honing the bore to a target size, as a function of at least the measured feed system position, the target size, and a predetermined value for tool wear as a function of feed system position; 
 determining a target feed system position for honing the bore, as a function of the predicted value for tool wear and the target size; and 
 honing the bore until the target feed system position is reached. 
 
     
     
       12. A method as claimed in  claim 11 , where in the step of expanding the tool, the tool is expanded at a predetermined rate. 
     
     
       13. A method as claimed in  claim 12 , comprising further steps of:
 retracting the tool in the honed bore, then expanding the tool therewithin, under the static conditions and at the predetermined rate, until the predetermined feed force is reached, and measuring the feed system position; 
 positioning the tool in a bore of known size and expanding the tool, under the static conditions and at the predetermined rate, until the predetermined feed force is reached, and measuring the feed system position; and 
 determining a feed system compensation value as a function of at least the measured feed system position for the tool in the bore of known size, and the measured feed system position for the tool in the honed bore. 
 
     
     
       14. A method as claimed in  claim 13 , comprising a further step of determining a new feed system target value as a function of the feed system compensation value. 
     
     
       15. A method as claimed in  claim 14 , wherein the feed system target value is used for honing a subsequent workpiece. 
     
     
       16. A method as claimed in  claim 11 , wherein the predetermined value for tool wear is determined from a determination of tool wear from honing bores of at least two previous workpieces. 
     
     
       17. A method for automatically honing bores of a plurality of workpieces to a target size, using a honing tool assembled to a honing machine feed system capable of measuring feed forces exerted against the tool and feed system positions representative of feed positions of the tool, comprising steps of:
 prior to honing the bores of at least some of the workpieces, respectively, expanding the tool within the bore of the workpiece in a predetermined manner, under static conditions, until a predetermined feed force is reached, and measuring the feed system position; 
 between the honing of at least some of the bores, positioning the tool in a bore of known size and expanding the tool in the predetermined manner, under the static conditions, until the predetermined feed force is reached, and measuring the feed system position; and 
 determining a target feed system position for honing each of the bores of the workpieces to the target size, respectively, as a function of the measured feed system positions and a predicted stone wear value. 
 
     
     
       18. A method as claimed in  claim 17 , wherein the predicted stone wear value is determined as a function of an amount of material to be removed from the bore by honing the bore.